Over the last 20 years, front wheel drive automobiles have increased in popularity to the point where the majority of new automobiles sold are front wheel drive. It is now well known that one of the most effective transmission and engine arrangements for front wheel drive cars utilizes a transmission and engine disposed at the front of the automobile, with the axis of the engine crank shaft being generally parallel with the front of the automobile and perpendicular with the rotational axis of the radiator cooling fan. However, this arrangement no longer permits the use of a fan mechanically driven directly from the engine as was done with most rear wheel drive automobiles. More specifically, rear wheel drive automobiles typically supported the engine with the longitudinal axis of the engine crank shaft perpendicular with the front of the automobile and parallel with the rotational axis of the radiator cooling fan.
Accordingly, front wheel drive automobiles normally use an electric motor to rotate the radiator cooling fan. These electric motors are powered by the automobile battery, alternator, and operate during engine operation (i.e. while the battery is charged by the alternator) or, in many cases after the engine has been turned off. Thus to conserve battery life, reduce power consumption and prevent inadvertent battery discharge, it is important that fans designed for this use produce the maximum air flow to cool the radiator for a given amount of energy applied to the motor. In addition to conserving energy, it is important to provide a radiator fan which is quiet during operation.
Various shrouding, fan and fan support designs have been devised for radiator and engine cooling to reduce fan-generated noise and to move air more efficiently. Among these are shroud assemblies fixed with respect to the radiator having cylindrical rings within which the fan rotates, banded fans, cylindrical ring and fan band combinations which interact to improve performance, and fan motor support fins which modify air flow using fan and stator configurations of the type described in Axial Flow Fans and Ducts, Wallis, R. Allen, pp. 231-241, John Wiley & Sons, Inc. (1983) (hereinafter "the Article").
In general, the Article teaches the design of a stator (e.g. radiator fan support) which uses electric fan motor supports having vane shapes such as, for example, those disclosed in U.S. Pat. No. 4,548,548. As discussed in the Article, "inadequate aerodynamic consideration of the consequences of certain bearing support and/or rotor drive systems often leads to operational problems. For example, the electric drive motor is often mounted on a bench plate spanning the duct, incorporating one or more radial stiffening plates. This limited array of plates is assumed, incorrectly, to perform a flow-straightening function. Instead flow separation from each plate leading edge will lower fan efficiency and create downstream flow problems." (The Article, p. 37.)
In addition to using various designs for stator supports, attempts have been made at also modifying fan blade designs to reduce noise, and increase efficiency. However, there still is a need for improved fan blade designs used in combination with airfoil shaped stator supports to move air past a radiator with improved efficiency and reduced noise.